Disclaimer: Supernatural © Eric Kripke; Doctor Who © BBC

"Well, no wonder you lot are having so much trouble with time travel," said the alien in the tweed jacket and bowtie. "Your equations are all wrong."

And with that, he wiped the board, previously filled with a set of partial differential equations on time travel, completely clean. Dean had to hide a smile at Castiel's subtly wounded face, watching as the strange bowtie-wearing alien that had introduced himself only as the Doctor began drawing, babbling away with his hands and mouth. " Most humans — and, I suppose, angels — assume that time is a strict progression of cause to effect, but it's more like a big ball of wibbly wobbly, timey-wimey."

"Wibbly-wobbly, timey-wimey?" repeated Amy Pond, the redhead that been with the Doctor when Dean, Sam and Castiel had stumbled across them in the forest. Now that they were back at Bobby's, she had taken great interest in their work, peppering Sam and Dean with questions about the use of salt, holy water and silver. Sam had just as many questions, and they had figured out several of their more stranger monsters were actually aliens. (Dean had always thought the jinn were too surreal to be anything but.) "Is that a technical term, Doctor?"

"Yes," the Doctor replied absently, marker squeaking on the board. His wibbly-wobbly, time-wimey equations, much like the theory of time, was written in great sweeping circles, with smaller circles and symbols linking the larger ones. Castiel's hurt look had faded and his eyes had widened comically, rapt interest all over his face. Dean wondered, briefly, if it was a bad idea to teach to teach a slightly sociopathic angel the finer points of time travel, but then he shrugged. What could possibly go wrong?

"So you guys travel through time and space, fighting monsters," Sam said to Amy, and she made a face.

"Well, not really. Mostly we stumble across a planet or place in need of help, he talks a lot, we run a lot, and the day is saved. Somehow."

"With my cunning genius!" the Doctor exclaimed, and Amy rolled her eyes. Then she smiled and shrugged.

"Sometimes there's guns though. And explosions." She winked. "And lots of monsters."

"Sounds like my kind of party," Dean drawled and they shared a grin. Sam's face fell.

"Wait. Does that mean... We're in dire need of help?"

Dean almost choked on his beer as Amy's eyes went wide. Sam had to ask that, Dean thought. Sam had to ask! They had been having such a good time, too! "Man, you just jinxed us!" he snapped, punching Sam's shoulder.

"I did not!" Sam protested with a squawk while Amy pulled out her phone. Before the two could start arguing, she held out her phone to show them.

It was a picture of one of the Supernatural books (in ebook format). On it were the usual hunky men, and the angel with his wings spread wide. Next to them was a man in a tweed suit and bowtie, along with a redhead with a rather large breasts. (The artist had clearly taken liberties). In the background, however, was a picture of a gigantic snake, which fit the title, Serpent of Eden.

"Oh, hell," Dean muttered and Amy winced.

"I haven't had a chance to read it yet," she said, waving her hand. "I'm still reading the Leviathan saga."

Dean and Sam exchanged a nervous glance just as the Doctor clapped his hands and said, "Well, Castiel, want to give it a go?"

Dean and Sam's glance fell to one of horror, and they both jerked their heads to the Doctor and Castiel. "Cas, no!" they shouted in unison, but it was too late. Already Castiel, with a giant grin on his face, had said, "Let's go to Eden to meet my father!"

Before they zapped away, Dean muttered, "You jinxed us, Sammy."

"I did not," Sam hissed and Dean grunted.

"Bitch."

"Jerk."